Micro-Resistivity

The micro-resistivity module provides a high- vertical-resolution micro-focused resistivity measurement within the flushed zone. The measurement electrodes are mounted on a flexible pad which is maintained in contact with the borehole wall by a motor-driven back-up/ caliper arm. The measurement pad is interchangeable to give a either micro-focused resistivity or micro-normal/ micro-lateral electrode geometries. The tool is stackable with all other RG slim oilfield probes. When combined with the dual laterolog it replaces the lower guard electrode.

Principle of measurement:

Micro-focused resistivity

A central current-injection electrode is surrounded by 3 concentric ring electrodes in a circular LL-7 configuration. The measure current is focused into a narrow beam which penetrates the mud-cake to give a resistivity measurement in the flushed zone (Rxo) beyond.

Micro-normal/ micro-lateral

Three in-line button electrodes, 1” apart, are configured to provide simultaneous 2” micro- normal and 1.5” micro-lateral measurements. Separation of the two measurement values due to their different depths of investigation gives an indication of mud-cake thickness.